Hardening photographic gelatin



Patented Mar. 14', 1944 HARDENIN G PHQTOGRAPHIC GELATIN Charles F. H. Allen and Charles V. Wilson, Roch-- ester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation oi New H Jersey No Drawing. Application October 10, 1942,- v

- Serial No. 461,634

9 Claims. (Cl. 957) come the tendency of the gelatin to melt, or toswell during development, particularly 'at high temperatures, by addition of various so-calledhardening agents, the most well-known of which appear .to be chronic alum and formaldehyde. Other materials such as acrolein, glyoXal and saturated diketone compounds have been proposed for this purpose.

We have discovered aznew class of hardening agents for photographic gelatin, namely, unsaturated aliphatic 1,4-diketone compounds, which are eminently suitable for the purpose. The compounds are effective in enabling gelatin emulsion layers and gelatin layers in general to resist swelling or melting, especiall at relatively elevated temperatures.

It is an object of the present invention to provide a process of hardening albuminous substances such as aliphatic 1,4-diketone compounds.

Another object is to provide a process of hardening gelatin emulsions for photography.

Another object is to provide a process of hardening gelatin solutions or layers, in general,

whether in the form of photographic emulsions or merely in the form of a separate layer or a coating on paper or other similar surfaces. Other objects will become apparent as our description proceeds.

In the present invention the above objects may be accomplished by incorporating into the gelatin emulsion or solution an unsaturated aliphatic 1,4- diketone compound, for example, diacyl ethylene such as diacetyl ethylene, dipropionyl ethylene, acetyl propionyl ethylene, etc.

In the following examples are set forth pre-' ferred embodiments of our invention, but they are included merely for p not as a limitation thereof Example 1 To a portion of melted photographic emulsion containing 12 grams of gelatin is added 0.05 gram of diacetyl ethylene in 5 cc. of alcohol. The emulsion is coated on a film base and dried, then allowed to stand in storage for ten days. When gelatin by means of unsaturated rposes of illustration and- ,ening agent, both emulsion containing no hardemulsions being processed at 85 F., it is found that the control emulsion softened in the developer, melted badly in the fixing bath, and mostly washed off of the support during washing. The emulsion hardened with dicoating of the same served during washing. I

A similar coating hardened with 0.1 gram of diacetyl ethylene in the same amount of emulsion gives an appreciably harder emulsion layer.

Example 2 A solution containing 12 grams of gelatin and a filter dye is treated with 0.1 gram of diacetyl ethylenein alcohol and castes 'alfilter layerlover the resulting emulsion is compared with a control provided with a hardened During processing of layer withstands the processing solutions without undue softening.

In a similar manner a gelatin filter is obtained a sensitive emulsion layer.

by incorporating in a solution of gelatin an amount of the hardening agent, generally an amount of the order of 0.1 gram or more of the hardening agent per twelve grams of gelatin, suflicient "to give the required degree of hardness, and the solution is coated on a suitable coating surface, for example, glass, paper, metal, etc., from which it is stripped after drying.

Di'acetyl ethylene maybe prepared by the method of Armstrong and Robinson, J. C. S. 1650 (1934) Homologues thereof may be prepared in a similar manner..

The above examples are, as indicated, merely may likewise be applied to the manufacture of gelatin solutions which are used for producing other types of coatings or layers on paper, cloth, film, and other surfaces. Also, the hardening agents of our invention may be used in conjunction with other gelatin hardeningagents, for example, aldehydes, and alum. A

What we claim is:

1. In the manufacture of photographic articles gelatin layer, the step which com-prises treating the gelatin with a diacyl ethylene.

2 I 2. In the manufacture of a photographic film provided with a gelatin silver halide emulsion layer, the step which comprises treating the gelatin with a diacyl ethylene.

3. In the manufacture of a photographic film provided with a gelatin silver halide emulsion layer the step which comprises treating the gelatin with'di'acetylethylene.

f1. An article of manufacture comprising a-sheet material having thereon a layer or the reaction product of gelatin and a diacyl ethylene.

5. A photographic material provided with a layer of silver: halide dispersed in the reaction product of gelatin and a diacyl ethylene.

6. A photographic material provided with a layer of silver halide dispersed in the reaction product 01' gelatin and diacetylethylene.

. menu.

9. A composition of matter comprising a solution of gelatin containing silver halide and diacetyl ethylene, said solution being adapted for the production of 'a hardened silver halide emulsion layer.

- CHARLES F. H. ALLEN.

CHARLES V. WILSON. 

